Bobs, I would venture to say a fully automatic transportation system would really reduce (if not eliminate in most cases) the amount of traffic on the freeways (bumper to bumper) due to the fact that human responses to events are much slower than computer based. Image how long it takes the last car in a 50 car single file line to start moving after the first car has. In a computer based system, they could all come close to starting at the same time. Humans also need a much longer space between vehicles due to our slow reaction time as well. If the space between vehicles went from 1 car length per 10mph, to say 1/10th of that, you effectively increased the amount of vehicles that a road can handle. Now when would such a system be around? Who Knows?
-- AMD_Dude